From 8db1226ae46b9c63275dcba1227e5d3c123fb258 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 30 Apr 2024 17:11:54 +0000 Subject: [PATCH] Use consistent byte/char offsets when parsing invoice HRPs When parsing lightning-invoice HRPs we want to read them char-by-char, tracking at which offset different fields were. Prior to this commit this was done first by reading char-by-char and then by indexing using the byte offset which works for ASCII strings but fails on multi-byte characters. This commit fixes this issue by simply always walking byte-by-byte and rejecting multi-byte characters which don't belong in HRPs. --- lightning-invoice/src/de.rs | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/lightning-invoice/src/de.rs b/lightning-invoice/src/de.rs index 56e5c53ba..c38aeb8a5 100644 --- a/lightning-invoice/src/de.rs +++ b/lightning-invoice/src/de.rs @@ -43,7 +43,11 @@ mod hrp_sm { } impl States { - fn next_state(&self, read_symbol: char) -> Result { + fn next_state(&self, read_byte: u8) -> Result { + let read_symbol = match char::from_u32(read_byte.into()) { + Some(symb) if symb.is_ascii() => symb, + _ => return Err(super::Bolt11ParseError::MalformedHRP), + }; match *self { States::Start => { if read_symbol == 'l' { @@ -119,7 +123,7 @@ mod hrp_sm { *range = Some(new_range); } - fn step(&mut self, c: char) -> Result<(), super::Bolt11ParseError> { + fn step(&mut self, c: u8) -> Result<(), super::Bolt11ParseError> { let next_state = self.state.next_state(c)?; match next_state { States::ParseCurrencyPrefix => { @@ -158,7 +162,7 @@ mod hrp_sm { pub fn parse_hrp(input: &str) -> Result<(&str, &str, &str), super::Bolt11ParseError> { let mut sm = StateMachine::new(); - for c in input.chars() { + for c in input.bytes() { sm.step(c)?; } -- 2.39.5